Azo dye and process of making.



UMTEE %TATE% FATENT @FFECE.

ERNEST FRANCIS EHRHARDT AND HERBERT WILEBI'D EHRHAEDT, 0F EDGBA$TON,

BIRMINGHAM, ENG-LAND.

No Drawing.

To all whom it may concern:

Be it known that we, Ennnsr FRANCIS Ennnann'r, B. Sc, D. Sc. Ph. 1)., and HER- BERT Wrnr'nm EHRHARDT, M. A.,B. Sc., both subjects of the King of Great Britain, residing at 409 Gillott road, Edgbaston, Birmingham, England, have invented a new and useful Azo Dye and Process of Making, of which ortho-,

acid with the cresol in caustic soda solution,

and precipitating the coloring matter by" means of hydrochloric acid. i The cresol from coal tar oil is now sold as or pale liquid carbolic acid, of a mixture of cresol'with some cresylic acid, and consists principally meta-, and para-, naphthalene and other bodies. Of the cresols. the para-cresol is the one which is always present in the smallest quantity. Even when the ortho-cresol has been separated from the mixture of cresols by distillation,

ortho-azo-coloring matters.

the resulting mixture of meta-, and para-, cresol usually contains about 60 per cent. of the meta-cresol and lOper cent. of the paracresol.

' The ortho-, and meta-, cresols form paraazo compounds. when combined with diazo compounds and combine far more readily than does the para-cresol which gives rise to The coloring. matter known as metachrome brown Y has recently been prepared by combining diazotized picramic acid with pale liquid earbolic acid, taking however considerably more than the theoretical quantity of the cresols and other bodies, con- Speeification of Letters Patent.

, matter, which, when pure,

Patented Get. 8, 1918..

Application filed January a, 1191s. Serial No. 210,820.

stituting the said pale liquid carbolic acid, only part of the cresols employed combining with-the 'diazotized picramic acid to form the azo coloring matter.

The, coloring matter so obtained dyes unv mordanted wool from the acid bath the yellow-brown color described in the aforesai ipiggification of Letters Patent 3698 A. D.

Upon experimenting with the efliuent from this manufacture of metachrome brown Y we have found that new coloring matter can be obtained therefrom by treat ing the said efiiuent with diazotized picramic acid which coloring mater dyes shades different from the shade obtainedfromthe metachrome brown Y, the difference being most pronounced when both the coloring matters are d ed, in any suitable way, on a'chrome mor ant; for example, by the metachrome, or theafter-ch'rome, process, the color obtained by the treatment of the efiluent giving a mu h darker shade, than the yellow-brown, I chrome brown Y and the dyeings bein fast ' against scouring and milling, the she e obtained from our new dyes thus dyed being usually an olive-brown.

The possibility 'ofthus obtaining new coloring matters from the said. efliuent, and the fact that this contains uncombined paracresol, has led us to make further experiments with'comrnercially pure cresols and we have found that the said darker coloring dyes a chocolate brown on unmordanted wool and olive brown on a chrome mordant, results from the combination of the diazotized picramic andis a new colorlng 85 acid with para-cresol matter of great value for dyeing wool, the shades produced being fast against scouring, milling and light.

The new coloring matter can therefore/be obtained according to our invention by treating with diazotized picramic acid not only liquor such as is obtained after partial comobtained from meta-- rltyand dyes Example 1.Productz'0n of the new colorz'ng matter by fractional combination.

Dissolve about 27% parts of meta-paracresol (that is a mixture of cresols containing about per cent. of meta-cresol and 40 per cent. of para-cresol) in about 500 parts of water, and 401} parts caustic soda solution of Twaddell and cool this with'ice to between zero and 5 centigrade. arate' vessel diazotize a paste of picramic acid, which is ascertalned, by titration, to

be the equivalent of about 11.4 parts of so-' dium nitrite, with that quantity of nitrite, using about 74.1 parts of hydrochloric acid of 1.14 specific gravity. When the diazotization is complete 0001 thediazo solution to between zero and 5 centigrade addto it 16 parts of soda and 28% parts of caustic soda solution 70 Twaddell and run it into the solution of meta-.para-cresol and stir the mixture thoroughly until combination is complete, then filter, so as to obtain the aforesaid metachrome brown Y coloring matter. fluent, and diazotize separately an amount of picramic acid equivalent to the quantity of cresol contained in the said motherliquor, or efiiuent. This will usually be the equivalent of about 39 parts of sodlum nirite. Cool the diazo solution to between zero and 5 centigrade, add six parts of soda and run this cold diazo solution into the cooled mother liquor, or effluent, obtained as aforesaid. Stir thoroughly until the combination is complete. Collect '-the new coloring matter by filtration and bring it to a standard strength of paste by stirring with water.

The metachrome brown Y ter first obtained dyes unmordanted wool a bright yellow-brown and dyes chrome mordanted wool a duller yellow-brown. The second coloring matter obtained by treating the mother liquor, or effluent, as aforesaid is our new coloring matter in a fair state of puunmordanted brown, and, with a chrome an. olive-brown color, fast light.

In the foregoing exam le it is, after the first combination, desirable: to test a portion of the mother-liquor, orfiltrate, by combining a small quantity of it with mordant, gives to milling and of nitrite using Collect the mother liquor, or cfof sul coloring matwool chocolate-- uct, cooling th the equivalent quantity of diazotized picramic acid, and makea test dyeing to see whether the comand if not,

combination to remove this excess of ortho-, or meta-, ,cresol. The diazotizat-ions and combinations should be elf care so that the end product is not contaminated with the decomposition products of the diazo compound.

The method of working described in the foregoing: example can be varied as follows :-After thefirst combination by treatment of the mixture 'of cresols with diazotized picramic acid and, before filtering, the combination liquor is acidified so that the coloring matter formed is obtained in the form of its free acid, which is soluble in water and the uncomblned cresol is set free. and then filtered; the eflluent'is cooled and returned to a combining tub, or like vessel, and made alkaline and combined with the second quantity of diazotized picramic acid to obtain the new coloring matter;

z'ng matter from; isolated pdm-cresol.

Diazotize the quantity of picramic acid ascertained by titration to be the equivalent of 48 parts sodium nitrite with that quantity for the diazo solution and furic acid containing cent. H for diazotizing. solution into an ice'cold solution of 75 parts of para-cresol in 3000 parts of water, 87 parts caustic soda solution 74 140 parts of soda. Stir thoroughly until the combination is complete, filter, collect, by filtration, the new col ring matter and mix it with water to a standard strength of paste.

- What we claim is 1. The manufacture of ortho-azo coloring matter by combining diazotized picramic acid with the etfiuent from the fractional combination of diazotized picramic acid with bination is complete, then filtering bringing the coloring matter so a paste by stirring with water;

2. he manufacture of ortho-azo coloring out 128' parts about 90 per ected .with great- The liquid is brought to the boilabout 3300 [garts of water Run the diazo.

a mixture of cresols, stirring till com- Twaddell and matter; by acidifying a combination liquor of a mixture of cresols with diaotized picram1c acid,

boiling and filtering the prode efliuent and rendering it a aline and combining with. it a further quantity of diazotized picramic acid.

' 3. he manufacture of ortho-azo coloring matter by combining acid with pa'ra-cresol,

4. ,The manufacture of ortho-azo coloring diazotized picramic 5. As a new articleof manufacture, color- I ing matter which dyes unmordanted wool from the acid bath giving chocolate-brown shades and which dyes wool With chrome mordant giving'olive-brown shades fast to scouring milling and light, which coloring Copies of this patent may be obtained for five cents each, by addressing the matter can be obtained by combining diazotized picramic acid with para-cresol.

In testimony whereof we have signed our .names to this specification in the presence of two subscribing witnesses.

ERNEST FRANCIS EHRHARDT. HERBERT WILFRID EHRHARDT.

Witnesses:

EDWARD CRAVEN, RICHARD B. Pnnnosn.

Commissioner of Patents,

Washington, D. G. 

